I have two 100 Watt Kyocera panels that easily charge a bank of 8 x 6V batteries (900AH) fully during the day, including concurrent usage of autopilot, fridge, etc. I have a setup where I can angle the panels but so far have rarely felt the need to do so. So for you needs I would think a 50W panel should be sufficient. agree with others on getting a good controller. However, do some homework on the different styles (MPPT vs PWM) and decide on which one fits your need. I was looking to augment my panels with wind and/or towed generators and found a dual charge controller, but have not made a final decision yet. One big payback I got was to go with better cabling. The PO on my boat had used a single cable from both panels to below deck, then hooked that up to two smaller cables to hook up with the controller amidships. Although in theory that should have been OK, the point where the cables were joined heated up so much by late morning that it seemed a fire hazard. It also meant that energy was being wasted. When I changed the cable to a hefty 6AWG and used a good copper connector, my charge at the controller increased about 10%.